Electronics
The stages of healing after an acute wound in an otherwise healthy person.
Ionophoretic transport is a technique that involves the movement of ions across the membrane. It is achieved by applying an external electrical potential difference, which enhances the transfer of charged molecules or drug carriers to enable efficient drug delivery. Another method is through minimal invasive active jet injection, also known as microneedling. This technique involves the use of a high-velocity jet to create pores in the skin, facilitating the transdermal transfer of molecules. While it has shown promise in drug delivery, the implementation of bulky microneedling systems might be challenging to integrate in a wearable drug delivery system. However, these active drug delivery methods offer exciting possibilities for targeted and controlled drug administration with minimised side effects.
“Minimal invasive active jet injection or microneedling involves the use of a high-velocity jet to create pores in the skin, facilitating the transdermal transfer of molecules.”
Such a smart system was developed by researchers from the University of Nebraska-Lincoln. The group designed a programmable smart bandage that utilised hollow 3D-printed miniaturised needle arrays (MNAs), roughly 2mm in length, to bypass the wound crust and the necrotic tissue to actively deliver drugs to the deeper layer of the wound. For active drug delivery, two miniaturised peristaltic pumps that could manipulate minute amounts of two different drugs with independent dosages were used. Microchannels were fabricated in a polydimethylsiloxane (PDMS) layer with a thickness of roughly 1.5mm. PDMS was used as it is flexible, has a low protein adsorption, a high biocompatibility and a good oxygen permeability. These microchannels were used to connect the micropump with the MNAs. To keep the whole system flexible and cost efficient, it was designed with two
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modules; a disposable module with the MNA islands and microchannel arrays; and a reusable module that housed the drug reservoirs, micropumps, power source and electrical circuitry. These two modules were connected by two flexible silicon tubes. The whole platform can be connected to smartphones via Bluetooth and programmed with an app to precisely control the flow rate. The minimum threshold of the pumps was determined to be 0.5V, which resulted in a flow rate of 43.6 μL min−1. In a recent study, the platform was tested using vascular endothelial growth factor (VEGF) delivery through MNAs on diabetic mice with wounds. The MNA-based VEGF group showed 95% wound closure, while the no treatment and topical VEGF groups had 40% and 50% closure, respectively.
A smarter future
The use of sensors for wound monitoring does come with some disadvantages, including issues related to marker specificity; flexibility and the longevity of sensors; their durability in moist and protein-rich wound environments; biofilm formation; and the need for reliable data management networks. Nevertheless, after further research and development, smart dressings may be a promising approach to improve wound management for chronic wounds, and in the process make it more cost-effective. The use of MNA- based patches for wound care might be an effective paradigm shift from the current methods that will be used in clinical wound care practices. Smart patches is an exciting field that combines various disciplines such as wearables, medical technology and sensor technology. Optimised wound care can be a game changer for hospitals and care facilities as it enables resources such as time and material to be saved. For this reason, the topic will also be discussed within the framework of the IVAM focus group on flexible and hybrid electronics as well as the focus group on medical technology in the coming years. ●
Medical Device Developments /
www.nsmedicaldevices.com
Designua/
Shutterstock.com
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